7. PROJECT SUMMARY/ABSTRACT Over 2 million Americans have opioid use disorders, and millions more misuse opioids. In communities severely affected by the opioid crisis, as many as 10% of newborns are affected by neonatal opioid withdrawal syndrome, which costs upwards of $1.5 billion annually. A large body of research documents the many negative consequences of being raised by a mother with opioid addiction, especially in infancy and early childhood. In addition, many mothers find that having a child is a strong motivation to seek treatment for their opioid use and/or addiction. For these mothers, there are currently no evidence-based parenting interventions to support them. Moreover, very little is known about mediators and moderators of the effectiveness of early childhood parenting interventions more generally (i.e., what works for whom and why), which limits the ability for researchers to identify how the systems targeted by these programs may be affected by opioid use. The overall objective of the proposed study is to conduct a randomized efficacy trial with a diverse sample of low- income families with children ages 0?36 months whose mothers are in or have been referred to treatment for opioid use and/or addiction. We will work with our Advisory Board and our community partners to adapt the evidence-based, scalable, Filming Interactions to Nurture Development (FIND) program to this treatment context (Aim 1), and then use a longitudinal randomized efficacy trial to test the central hypothesis that associations between increases in responsive caregiving (the main FIND target), and subsequent caregiver well-being and child developmental and biobehavioral outcomes (secondary targets), will be partially mediated through changes in caregiver inhibitory control (measured behaviorally and with neuroimaging methods) and parent self-concept (Aims 2-3). The rationale for this work is that it simultaneously addresses the unmet needs of a vulnerable, significantly underserved early childhood population and allows for a rigorous test of our conceptual model. We will randomize 200 primary caregivers and their 0- to 3-year-old children to receive FIND or an active control intervention (all participants will receive addiction treatment from their referral source). Aim 2 quantifies the main effects of FIND on changes in responsive parenting and related caregiver and child outcomes immediately after the intervention, and the durability of these effects 6 months later. Aim 3 explores underlying neural mechanisms that mediate associations between FIND-related changes in caregiver behavior and caregiver/child outcomes and the specificity of those mechanisms, and assesses the degree to which these associations are moderated by neonatal opioid withdrawal or abstinence syndrome. Within-group analyses will also examine intervention fidelity and dosage. This information is critical to addressing differential response to early childhood interventions for children ages 0?3, to increase impact and scalability. These outcomes will have a positive impact in that there are currently no evidence-based, early childhood parenting interventions designed to be implemented in a treatment setting. An easily delivered program that can be provided while these parents seek treatment for opioid misuse may facilitate their children's development and reduce risks.